next-generation (now) MPU discussion / Backup battery on PMU only

Andy Green andy at
Fri Apr 25 09:07:04 CEST 2008

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Somebody in the thread at some point said:
| Andy Green wrote:
|> I think there is a bit of confusion here.  "Standby" is a separate issue
|> that does not need battery backup on MSP430.  IO_3V3 rail is up during
|> standby.  MSP430 will be up during standby.
| Not quite :-) PMU.Standby != Linux.suspend

Then a wise person would disambiguate it when they talk about it,
because "standby" is normally what we use to talk about global device

| When we suspend, the CPU remains in PMU.Active, and all we do is switch
| off some of the regulators we don't need. This is your scenario where
| IO_3V3 is active.
| However, PMU.Standby really means "no power to the system". (You can

There was plenty written there about the PMU.  But the issue was about
who gets to drink our precious backup battery.

''The ONLY scenario we consider is no external power, and battery is
removed.  Why do we need MSP430 state to survive it?   I don't think we
need this since we only want RTC to stay up and the RTC can be in PMU.''

- -Andy
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